In last summer's "Scary Movie," director Keenen Ivory Wayans ridiculed "Scream" and other post-modern horror films. There were a few grossly amusing moments  emphasis on the "gross." But the fun was diminished by the self-mockery of Wayans' targets, which were already toying with slasher-flick orthodoxy. In this sequel, the humor is even more scatological  and not as sharp. Yes, it parodies other scary movies, principally the haunted-house variety. Anna Faris returns as lead ingenue; co-stars/scripters Shawn and Marlon Wayans are back; Tim Curry and Chris Elliot provide intermittent giggles; a few take-offs and topical jokes hit their targets. Echoing an old "SNL" skit, a pell-mell prologue skewers "The Exorcist," with a slumming James Woods and ex-Conan O'Brien sidekick Andy Richter as two dorky priests trying to chase a demon from a possessed girl, played by an unrecognizable Natasha Lyonne. It's downhill from there, and all that's scary is the idea of a "Scary Movie 3."